All those potential collectors who keep asking about talented artists not yet "discovered" should run, not walk, to the Fendrick Gallery, 3059 M St. NW, and buy, not just look at, the work of Barton Benes. Next time he shows here, his prices may well have gone out of the ballpark.

Benes was first introduced at Fendrick a few years ago in a show of handmade artists' books, to which he submitted among other things, a "Trashy Novel," which consisted of an actual novel stuffed with trash, painted, and transformed into a sculpture.

He later began to concentrate on objects decorated with excerpts from letters written by his real-life Aunt Evelyn, an aging recluse who used to write 50-page, stream-of-consciousness letters twice a week -- before she discovered what he was doing with them.

Using rubber stamps from his huge collection (he has been called, "the king of rubber stamps,") he hand-printed Aunt Evelyn's words about Halloween and poisoned cookies on a rolling pin; her account of a trip to the supermarket upon a grocery bag; her tale of a good cry on several embroidered hankies. Like the words themselves, these works are sometimes funny, sometimes sad, always poignant.

Meanwhile, Benes was also making objects out of seashells -- absolutely outrageous objects, culminating in the 5-foot-tall, shell-covered classical column with a Griffon on top, actually an elaborate incense burner. It is in the current show.

In this show, entitled "Ruins and Artifacts," Benes' seemingly boundless imagination moves on in various formats, including a group of what at first appear to be ancient pot shards, but on closer examination turn out to be bits of smashed clay flowers pots, painted and rubber-stamped with contemporary words and images. One of the most powerful, "The Dance," is rubber-stamped around the rim with 1920s couples dancing, and below excerpts from Aunt Evelyn's account of her cousin's dancing class in a retirment village.

Also entirely new in this show is a series of rubber-stamped "drawings" on paper, all forming handsome, elaborate designs that look, in the end, like Persian rugs and manuscripts, though one is made chiefly of the letters S.O.S. Most beautiful of all are those done on colored paper, which he calls "Illuminated Manuscripts," enhanced by rich colored inks and gold, and centered with text, once again, from Aunt Evelyn. One called "Thanksgiving, 1976," begins with "I missed Thanksgiving day completely. I goofed." It is among the most beautiful works on paper Benes has ever made. The show continues through Dec. 8.

Martin Puryear is another artist collectors should be snapping up right now, though since his inclusion in major shows at both the Guggenheim and Whitney museums, that is less of a secret in New York than it is here. His show of new work at Protetch-McIntosh, 2115 P St. NW, reveals him to be getting better and better all the time.

Puryear is a master at conjuring a feeling, a mood, with very minimal means. This show, for example, is devoted entirely to large, wall-hung loops of various sorts, all made from a variety of woods that have been bent, carved, constructed or coaxed into large hoops, each exuding its own distinctive and very different mood. Some are smooth, slinky and sensuous, others are slick and modern, others carved, polychromed and seemingly of primitive origin. Through Dec. 15.

Diane Brown, 2028 P St. NW, is showing new work by Jennie Lea Knight, Washington sculptor, who when last observed was combining milled wood and branches into rich, highly formal, often highly poetic compositions.

In this show, Knight has moved boldly forward, expanding her vocabulary of forms in more playful, more experimental sculptural assemblages that include not only wood but also thin metal rods and, most important, ceramic elements.

The introduction of various ceramic forms of her divising -- sometimes limp and sensuous like fabric, sometimes hold and monolithic like stone -- adds a new dimension of possibilities that Knight is just beginning to explore in this show. From the endearing "Nest Piece," to the commanding "Plug," a beaver-gnawed branch wrapped in clay, Knight proves an ability to move successfully into a broader expressive realm than she has attempted in the past. Through Nov. 29.

Bern, the ancient, flower-bedecked capital of Switzerland, is not where you'd expect to find avant-garde art. The Bern Kunsthalle, however, a city-supported gallery of contemporary art, is among the more advanced in Europe. It was the subject of Christo's first wrapped building, and host to shows by Sol Lewitt, Carl Andre and other American minimal and conceptual artists long before they were exposed in American cities outside New York.

While that is a subject of considerably larger scope than the small show of works on paper now on public view at the Embassy of Switzerland, 2900 Cathedral Ave. NW, it provides some insight into why so many Swiss artists have settled in or near Bern. A sampling of the best has been selected for "Eight Artists from Bern," on view through Dec. 1, Monday through Saturday, 9 a.m. to 5:30 p.m. Ruth Mentha, a Bernese artist and dealer, made the selection.

Anyone who recalls the famous furlined teacup, the Museum of Modern Art's surrealist relic by Meret Oppenheim, will be both pleased and possibly surprised to discover Oppenheim among the Bernese artists represented here. Now 66, this artist is still devising highly original images in a whimsical surrealist mode, and the recent lithographs are by far the strongest works in this show. Oppenheim also turns out to be a woman -- a fact that has slipped by this viewer and possibly others. There's obviously a lot more to her than most of us have realized.

Among the other artists in this show are Rudolf Mumprecht and Roland Werro, whose works recall the calligraphic instincts of another Bernese artist, Paul Klee.

Touchstone Gallery, 2130 P St., is showing, through today, the work of two gallery artists -- stripe paintings by Janet Wheeler and monoprint etchings by Mansoora Hassan. Hassan has come a long way since her last show, and though some of her images are still muddled, there is, in others, a new clarity. When that gets together with warm, rich color, Hassan is at her best.

Janet Wheeler's paintings consist chiefly of dark backgrounds from which thin horizontal stripes of color zing back and forth into space, establishing a great variety of outposts within the illusionary depth of the canvas. Best of all are the smaller works on paper, which also involve collage and which manage to sustain surface sometimes lost in the larger, dark expanses.